Spouses or partners who live together both tend to lose weight when one of them goes on a weight-loss diet. A study published in the journal Obesity followed 130 overweight adults on a Weight Watchers diet or a self-guided diet. After six months, the Weight Watchers plan had yielded average losses of about nine pounds, and the self-guided diet about seven. The spouses and partners—who were not invited to participate in the diets—lost a bit more than four pounds on average.
“Weight within couples is highly interdependent,” wrote the authors of the study, who noted that “spouses often enter marriage at a similar weight status and mirror each other’s weight trajectories over time.”